Handgun, that is not on a the handgun roster certified for sale, breaks and when contacting manufacturer, deems that the firearm will be replaced. They will be sending a handgun with different serial number.

I know that the handgun has to be delivered to a FFL, but does it end there?

Since the handgun is not on the roster, will the FFL be unable to transfer the handgun to the owner who got a warranty replacement? Or, will the owner be able to take possession after going through transfer process of receiving the handgun because it is not a sale, but a "transfer". Or, will the firearm owner have to go about exempting from the roster by doing SSE?

If you have a gun that needs to be sent in for warranty work you can send it to manufacture if the manufacturer deems it's not repairable it needs to replace that they fill out a form and file it with the state in the Fed stating that they swapped out serial number 12340 number 456 and ship it back to you since you legally possessed and off roster handgun prior to shipping it and there are no issues as you're not buying a new weapon they are simply swapping one out under warranty P

If the firearm is replaced, it needs to be DROS'd. It is not the same firearm and the new firearm can not just be sent to the person who sent it in unless the manufacturer duplicates the serial number on the new firearm.